Control system for single-phase motors.



I I Hun I v g/ R. E. HELLMUND CONTROL SYSTEM FOR SINGLE PHASE MOTORS.

APPLICATION FILEDf'EBJQ. m4.

1,224,166. Patented May 1, 1917.

" 32, INZENTOR 5 I2 7 BY 5 g I Z Afiormzv I UNITED STATES. PATENTOFFICE.-

RUDOLF E. HELLMUND, F PITTSBURGH, PENNSYLVANIA, ASSIGNOR .TO WESTING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

To all whom it may concern Be it known that I, RUDoLF E. HELL- MUND, asubject of the German Empire, and

, Control Systems for Single-Phase Motors,

a resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in of which thefollowing is a specification.

My invention relates to dynamo-electric machines, and it has specialreference to means for operating alternating current motors of thecommutator type.

One object of my invention is to provide means for automatically aidingthe acceleration of a motor of the above-indicated type andsimultaneously maintaining good commutating conditions therein.

' winding, and inversely proportional to the voltage of the main orexcitin field winding, it follows that, if commutating flux values inthe machine are varied in accordance with the ratio referred to, thatis, indirectly in proportion to the change in motor speed, thecommutating conditions 'will'be good throughout the starting period ofthe motor, and sparking and flashing troubles heretofore experienced inthe operation of machinesof the type in question will be obviated.

According to my present invention, I pro- Vide an alternatingcurrentsinglephase motor that is adapted to start as a repulsion motor, that isto say, with the armature winding initially short-circuited, and anelectro-responsive device that is differentially subjected to thecombinedinfluence of the armature and the inducing field windings and ofthe exciting field winding,.and that is adapted to automatically openthe short-circuit of the armature, at the proper time, to furtheraccelerate the motor and to simultaneously maintain good commutatingconditions in the machine.

In one form, my invention comprises-the combination with an alternatingcurrent Specification of Letters Patent.

CONTROL SYSTEM FOR SINGLE-PHASE MOTORS.

Patented May 1, 1917.

Application filed February 19, 1914. Serial 110 819338.

motor of the commutator type, of an electroresponsive device, such as arelay, having three cores, the coils of which are independentlyconnected to the armature winding and the two field windings of themotor. The coils are connected in such manner that those associated withthe armature and with the inducing field winding are adapted to exert apull in one direction,-and the coil connected to the exciting winding isadapted to exert a pull in the opposite direction.

In modifications of my invention, I em-' ploy a relay having two cores,the coil of one of which is connected across the exciting field windingand the other coil is connected either across the inducing field windingand the armature winding, or across the inducing field Winding and inseries with the secondary winding of a transformer, the primary windingof which is connected across the armature. A switch for normally shortcircuiting the armature winding is secured to the cores of the relay, ineach form of my invention In addition, a suitable device for holding theshort-circuiting switch 'open, when it has once been actuated by therelay, is also provided.

In the accompanying drawing, Figure 1 is a diagrammatic view of acontrol system embodying my invention, and Figs. 2 and 3 are similarviews of modifications thereof.

Referring to the drawings, the system here shown comprises a supplycircuitl; a suitable auto-transformer 2, or the equivalent, connectedthereto; an alternating current motor of the commutator type having anarmature winding 3, a main exciting field winding 4, and an auxiliary orinducing winding 5; a plurality of main-circuit switches S and S anelectro-responsive device 6 connected to the motor, as hereinafterdescribed; a switch 7 associated with the device 6 for normallyshort-circuiting the armature winding 3; and anainterlocking device 8associated with the switch 7.

' The electro-responsive device 6 is provided with three cores 9, 10 andll; the actuating winding for the core 9' is connected across theinducing field winding 5 and, as shown in the drawing, is adapted toexert an up; ward pull on the core. The actuating coil for the core10.is connected across the armature winding 3 and is also adapted toexert an upward pull. The actuating coil for. the I .and 11 inopen-circuit position.

core 11 is connected across the exciting field winding 4 and is adaptedto exert a downward pull on the cores. It will thus be observed thattheelectroresponsive device 6 is subjected differentially to thecombined, I

quently, the combined armature and inducing field-winding voltages maybe referred to as the total armature working voltage, taking phasedisplacement and the trans-- former ratio into account.

The interlocking device 8 may be of any suitable and well-knownconstruction for holding the movable member of'the switch 7 and itsmechanically associated cores 9, 10

The device 8, as shown, comprises a spring-pressed rod 12 for engagingthe movable member of the switch 7 and an actuating coil 13 for movingthe rod 12 in opposition to its. biasing spring to permit the switch toclose.

' Reference may now be had to Fig. 2, in which is shown anelectro-responsive device 14 comprising two movable cores 1'5 and 16.The coil for the core 16 is connected across the exciting field winding4 and the coil for the core 15 is connected across the inducing fieldwinding 5 and is in series with the secondary winding 17 of a seriestransformer, the primary, winding 18 of which is connected across thearmature winding and the exciting winding, is secured to theelectro-responsive device 1&1. The remaining portions of the systemshown are similar to those described in connection with Fi 1.,

fieferring now to Fig. 3, the system shown comprises amotor embodyingthe features of those shown in Figs. 1 and 2, 'and,-in addition, havingan auxiliary interpole winding 19 connected to the inducing winding 5for commutating purposes. .An electro-re'sponsive device '20 comprisestwo movable cores 21 and 22, the collfor the core.21 beingconnectedacross the interpole and inducing field windings 19 and 5 and thearmature opposite directions.

winding 3, and the coil for the core 22 being connected across theexciting field winds ing 4. As in the systems hereinbefore described,the coils are arranged to pull in The interlocking dev1ce 8 is againprovided, as described with reference to Fig. 1.

The operation of the system of Fig. 1

count will be given here.

may be described as follows: Energy from any suitable external source isfirst momentarily supplied to the coil 13 of the interlocking device 8for actuating the rod 12 to allow the movable member of the switch 7 todrop to its closed position, thus initially short-circuiting thearmature 3. Alternating current of a suitable potential isthen suppliedfrom the auto-transformer 2, the switch'S being closed for starting themotor. When the combined voltages of the accelerating armature winding 3and of the inducing winding 5 have risen to a sufficient value toovercome the action of the electro-motive force impressed across theexciting field winding 4, the electro-responsive device 6 will beactuated to its upper position and will subsequently, be held in thatposition by the spring-pressed rod 12. In this way, the motor isinitially accelerated as a repulsion motor and, when operatingconditions are correct, as hereinbefore explained, the motor isautomatically changed over from a repulsion-type motor, the switch Spreferably being closed at this time to provide the doubly-fedconnection, in accordance with afamiliar practice; thus, the

motor is suitably accelerated and, at the same time, the commutatingflux therein is gnaintained at a proper value during the startingoperation;

It is believed that the operation of the systems of Figs. 2 and 3 willbe understood in connection with the above description and,consequently, no extended further ac- In the system shown in Fig. 3, theswitches S and S may be operated substantially simultaneously with theactuation of the electro-responsive device 20, or S may be operated atthat time and S subsequently, depending upon the design of the motor andthe commutatin'g'conditions that obtain, in accordance with a familiarpractice. Moreover, it will be un derstood by those skilled in the artthat electro-responsive devices similar to those described above may bereadily adapted for.

other purposes, such as cutting off the supply of energy, or setting thevehicle brakes. Furthermore, although, for illustrative purposes, I havedisclosed the electro-responsive devices as adapted to perform only oneoperation and thento be held inoperative by the interlockingdevice 8, itshould be ob-- served that the electro-responsive devices may beemployed, if desired, to effect other or subsequent circuit changes andacts.

Variations in the circuit connections and in the arran ement of partsmay be made within the splrit and scope of my invention, and'I desirethat only such limitations shall bf imposed as are indicated in theappended c aims. Y

" I claim as my invention:

1. The combination with a supply circuit,

' and a dynamo-electric machine operated therefrom and having anarmature winding and anexciting and an inducing fieldwinding, ofelectro-responsive means adapted to and to simultaneously maintain goodcommutating conditions therein.

2. The combination with a supply circuit and an alternating currentmotor of the commutator type operated therefrom and having an initiallyshort-circuited armature windingand an exciting and an inducing fieldwinding, of electro-responsive means adapted to be differentially actedupon in accordance with the respective voltages of said exciting fieldwinding and of the com bined armature and inducing field windings,

' 50 ing voltage. a

during the starting of the motor, to auto matically remove the armatureshort-circuitto further accelerate the motor and to simultaneouslymaintain good commutating con- 2 ditions therein.

3. The combination with a supply circuit and a dynamo-electric machineof the com- .mutato'r. type connected thereto and, having an armatureWinding and an exciting andan inducing field winding, of automatic meanscomprising a coil conductively connected to said exciting fieldwindingand a coil conduc'tively connected to said inducing field winding forvarying the commutating flux in the machine in accordance [with therelation existing between the exciting field strength and/ the totalarmature working voltage.

4. The combination with a supply circuit 40 and a dynamo-electricjmachine of the commutator type connected thereto and having an armaturewinding and an exciting and an inducing field winding, of automaticswitching means for varying'circuit connections to vary the commutatingflux in, the machine,

said means being j actuated in" accordance withthe differential relationexisting at a f predetermined time between theexciting field strengthand the total armature work 5. The combination with a dynamo-electricmachine having an armature winding ance with the additively combinedvoltages of the armature and the inducing field windj ing minus thevoltage of the exciting field winding.

- 6; The combination with a dynamo-electric machine having an armaturewinding and an exciting and an inducing field winding-,of a switchingdevice for making certain circuit connections, and two actuating coilstherefor, one of said coilsis conductively energized from said excitingfield winding and the other one of said coils is energized from saidinducing field winding.

7. The combination with a dynamo-electric machine of the commutator typehaving an armature winding and an exciting and an inducing fieldwinding, of a switching device for making certain circuit connections,and two actuating coils therefor, one of said actuating coils isconductively energized from the inducing field winding and isinductively energized from the armature winding and the other actuatingcoil is conductively energized from the exciting field winding.

8. The combination with a supply circuit and an alternating-currentdynamo-electric machine of the commutator type having an armaturewinding and an exciting and an gized from the exciting field windin anda transformer having its primary win ing directly energized from thearmature winding and its secondary winding connected in circuit. withthe first mentioned actuating coil.

In testimony whereof, I have hereunto subscribed my 1914.

RunoLF' E. HELLMUND.

Witnesses:'

' B. B. Hrmzs,

-M. G. MuRz.

name this Mthday of Feb,

